Hello everyone, this my real first OOP game, i used to do all my programs in one class, i followed some tutorials and then tried to remake a pong game that i already made but everything was in one class, but i don't want to do that anymore, things becomes really complicated when i want to fix or re-do something with it, i always get lost in the code,so, here is all the codes for the new pong and the error is :

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